Combination thermograph and hygrograph.



A. G. MOADIE. COMBINATION THERMOGRAPH AND HYGROGRAPH.

APPLIO ATION FILED MAR. 22, 1910.

974,684. Patented Nov. 1, 1910.

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ALEXANDER G. MGADIE, OF SAN FRANCISCO, CALIFORNIA.

COMBINATION THERMOGBAPH AND HYGROGRAPH.

Specification of Letters Patent.

Patented Nov. 1,1910.

Application filed March 22, 1916. Serial No. 551,023.

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' dress is San Francisco, California, have invented a new and useful Combination Thermograph and Hygrograph.

This application is made under the act of March 3, 1883, chapter 143 (22 Stat., 625), and the invention herein described and claimed may be used bythe Government of the United States or any of its officers or emloyees in the prosecution of work for the.

overnment, or any person in the United States, without payment to me of any royalty thereon.

My invention relates to a combination thermograph and hygrograph ada ted to record the de ree of temperature and simultaneously in icate the percentage of saturation.

The object of my invention is to produce an instrument which will record temperature and at the same time give a reliable and ready record of the percentage of saturation, reducible in grains of water vapor per thousand cubic feet, or any unit of volume which may be selected. The instrument is specially designed to enable fruit'growers and agriculturists in general to study atmospheric conditions intelligently for the purpose of ascertaining the times when frost is impending. Ithas been known for along time that on nights when the relative humidit was high a fall in temperature was less likely to 'be followed by frost with injurious effect upon vegetation, than on nights when the relative humidity was low. Heretofore, it has been the practice to use the dew-point in foretelling frost. It is, however, not easy to use any of the ordinary forms of dew-point apparatus to accomplish this purpose. Tables are re uired and computation is necessary. No orm of the dry and wet bulb thermometer, the sling psychrometer or whirling apparatus known to the inventor gives a continuous record of temperature and humidity in such a manner that a fruit grower may readily determine what is known as the saturation deficit.

frost, but it is necessary for the intelligent application of these methods, that the fruit grower shall know as much as possible of weather conditions, particularly with respect to temperature and the water vapor content. My invention will enable fruit growers to observe such temperatureand degree of saturation and thereby determine the probability of the occurrence of frost.

My invention is furthermore adapted for use in hospitals, assembly rooms, curing and drying rooms, or for any pu ose where know edge of what may be calle in ca acity of the air is needed.

it the above stated general objects in view, as Well as other objects which will .ap-

ear from the specification and claim to ollow, the invention resides in the novel construction, combination and cooperation of parts hereinafter described, and particularly pointed out in the claim.

-In the drawings, Figure 1 is a side perspective view of my invention, and Fig. 2 is also a side perspective View of my invention showing the hair arrangement.

. Referring to the drawings, A'represents a revolving cylinder or chronograph, driven by clock work. On this cylinder, A, a sheet the dryof paper, B, properly graduated according to the desired use of the instrument, is.

thermograph outfit. This outfit consists of the usual mechanical parts employed for operating the ordinary thermograph.

E is the metalliccoil arranged to give motion by expansion and contraction with the change in temperature, of a long index arm or pointer, F. The metallic coil, E, may be ma e of any suitable material that is sen: sitive to heat or cold, and its arrangement is not dissimilar to the coils used for this purpose in well known thermographs. Any coil which will perform the function desired can be employed in my invention. On the end of the index arm, F, is a pen or pencil, G. The purpose of this penci G, is to record on the graduated paper, B, the rise and fall of the temperature as the index arm or pointer, B responds to the action of the coil, E. In this manner, an accurate record of the various changes in the temperature may be made.

H represents the lower-index arm, at-

tached to the index arm, F, by meansof a pivot, J. The index arm, H, is movably arranged on the pivot, J, and is adapted to record its movements on the graduated paper, B, conveniently. The movement of the in dex arm, H, is regulated by a strand of hairs, L, which are attached at a point on the rear of the index arm, F, indicated by the letter, M, and extending lengthwise to a point on the rear of said arm indicated by the letter, N. The hairs L, rest on a hook or chain, 0, which is adjustably attached to the arm, H, by means 'of an adjusting screw, P. This hook, O, hangs over the arm, F, in such a position as to leave its supporting part in the rear of the arm or pointer, F, for use in supporting the strand of hairs, L. These hairs, L, are sensitive to moisture, i. 0., the vapor particles in the air, and are adapted to lengthen, stretch on contract under saturation pressure. The lengthening or contracting of the hairspL, depends upon the extent and effect thereon of saturation pressure. Any change in the tension of the hairs, L, produces a movement of the book, 0. The motion of the hook, O, is communicated to the index arm, H, by reason of the hook, 0, being attached to said arm, and this motion causes the same to move upward or downward according to the degree of tension of the hairs, L. I do not confine myself to the use of hairs for accomplishing the object described, but any other forms of hygroscopic substances may be employed to perform said function.

Attached to the end of the index arm, H, is a pen or pencil, I, which serves to record on the chart or paper, B, the movement of the index arm, H.

R R represent the weights for counterpoising the index arm or pointer, F. A celluloid,'a1uminum or paper scale, Q, properly graduated and out not straight but in arc, 1s suspended from the arm or pointer, F, and hangs in the rear of the arm or pointer, H. This are, Q, is adapted to indicate the degree of saturation. The reading is accomlished by observing the top edge of the ower arm or pointer, H. The percentage mark shown at the top of said pointer is the percentage of saturation. When the pens or pencils, G and I, are close together, the percentage of saturation is very small, and when said pens or pencils are wide apart, the percentage of saturation is large.

The index arms or pointers, F and H, may be constructed of German silver, thin brass, steel or aluminum, or other suitable material, as may be desired.

In practicing my invention", I place the instrument in a proper shelter and give it suitable exposure, thus subjecting the apparatus to become sensitive to temperature and moisture in the air. The degree of temperature is recorded on the chart or paper, B, which is properly graduated, by the heat coil, E. This tracing of the movements of the arm or pointer, F, on the chart or paper, B, enables the observer to read at once the degree of temperature recorded. The

lower index arm or percentage pointer, H,.

riding upon the first index arm or temperature pointer, F, responds to temperature changes, in traveling with the lon arm, F,

but it also has a proper motion 0 its own,

determined by the change in the length of the bundle or strand of hairs, L. This motion is produced by the changing of atmospheric conditions, which necessarily causes the hairs, L, to contract to stretch or expand. The changing of atmospheric conditions causing the hairs, L, to contract or lengthen, as the case may be, induces the hook, 'O, to move either upward or downward according to the degree of saturation in the air. The hook, 0, being attached to the arm or pointer, H, necessaril communicates such upward or downward motion to said arm or pointer. The upward or downward motionof the arm or pointer, H, determines the percentage of saturation in the air.

In determining the percenta e of saturation in air by the instrument escribed, use is made of a law of physics, viz: that for any given temperature there is at saturation a definite weight of water vapor present. As temperature changes, the saturation pressure changes, thesaturation pressure being the pressure exacted by the vapor particles. The weight of the aqueous vapor, sometimes called the absolute humidity, is

given by my invention directly on scale read-- mg for difl'erent temperatures. A range of temperature from 20 F. to 60 F. is printed on the paper, B, and temperatures may be read to half a degree between these limits. There is also printed on the said paper, B, opposite to the said range of temperature, the corresponding number of grains of water vapor at the given temperature in a thousand cubic feet of space. The metric system may be employed to efl'ect such reading and I consider this the preferable system to use. Corresponding metric values would be -6.7 C. to +15.6 C. and the weights per thousand cubic meters of saturated vapor 2870 grams to 13182 grams. The arc, Q, contains a scale showin the percentage of saturation. The reading is direct and little computation is necessary, and what there is is in tenths. For example: Suppose the upper index arm or pointer, F, indicates 2800 10 claim A combination thermograph and hydrograph, consisting of a cylinder driven by clock work, having a paper attached thereto properly graduated, and the saturation content printed in weight thereon for given temperatures, a coil adapted to expand or contract with any change in temperature, a support therefor, an arm in contact with said coil, an arm in contact with said coil I having counterbalancing weights at its rear end and a pencil at its front end, resting on said paper, said arm having an upward or downward motlon lnduced by the'expansion or contraction of said coil, said pencil tracing the movements of said arm on the said paper, thereby recording the degree of temperature, said arm having movably attached thereto at a lower angle and responding to its motion a second arm, said lower arm having a pencil at its front end, a hook attached thereto and connecting a strand of hairs arranged lengthwise of the rear side of said first mentioned arm,'said' hairs being adapted to lengthen or contract with the change of saturation pressure thereby subjecting said hook to an upward or downward motlon as the said hairs lengthen or contract, said hook communicating such upward or downward motion to the lower arm, said arm having contact with said paper and tracing its movement thereon, a percentage scale suspended from said first mentioned arm, said apparatus being adapted to record simultaneously the degree of temperature and indicate the moisture content in weight and percentage of saturation deficit, substantially a described.

In testimony whereof, I afiix my signature in the presence of two subscribing wit nesses.

ALEXANDER G. McADIE. Witnesses:

WILLIAM J. REED, WALTER H. SCHOLL. 

